Control of solar absorption and/or thermal emissivity is important for temperature control involving systems where radiation is the major heat control mechanism. Control of black body radiation and solar absorption, using spectrally selective coating, will help control the temperature. But, when the heat load varies, active control of the thermal radiation is needed. Coolants have been used to conduct heat to an external radiator and can be controlled to block, or to be open, to piping. Louvers are another alternative that can be used to open or close. With a louver in one position, the exposed surface will have a high emissivity; alternately when the louvers is in the other position, the exposed surface will have a lower emissivity and will radiate less heat. When radiators are fixed, as in present art, options including heat pipes, heat pump systems, capillary pump looped heat pipes and louvers can be effective but are expensive, heavy and bulky.
Electrostatic forces have been used previously in various applications.
U.S. Pat. No. 4,665,463 (1986) to Ward et al. describes an electrostatic chuck for holding a semiconductor wafer, comprising a dielectric layer on a supporting electrode. A potential is applied between the wafer and the electrode and the dielectric is loaded with thermally conductive material to improve dissipation of heat generated in the wafer during a processing treatment such as exposure to an electron beam.
U.S. Pat. No. 4,771,730 (1987) to Tezuka et al. describes a vacuum processing apparatus with a vacuum vessel within which a work to be processed is drawn and held fixed on a specimen table by an electrode functioning doubly as an electrostatic chuck, to which is connected a gas feeding pipe for feeding a gas affording good heat transmission between the mutually contacting surfaces of the work and the electrode to control the temperature of the work.
What is needed is a smaller, less expensive, flexible, lighter weight, higher performance, and more reliable solution. The present invention solves these problems with use of an electrostatic switched radiator.